Aqueous polymeric dispersions, methods of making the same and sized fiber tows

ABSTRACT

Various embodiments disclosed relate to an aqueous dispersion. The aqueous dispersion includes a plurality of particles. Each of the particles includes a polycarbonate component. Individual particles of the polycarbonate component have substantially the same size. The dispersion further includes a plasticizer component and a surfactant component. In an embodiment, a sized carbon fiber tow can comprise: a polycarbonate sizing on a carbon fiber tow, wherein the polycarbonate sizing has a concentration of volatile organic compounds less than 10 ppm, preferably less than 5 ppm, or less than 2 ppm; and an average sizing content of at least 0.5 wt % of the carbon fiber tow with a coefficient of variation less than 15%, preferably less than 11%.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application Ser. No. 62/539,859, filed Aug. 1, 2017, and to Indian Application Serial No. IN/2017/41027229, filed Aug. 1, 2017, both of which are incorporated herein in their entirety.

FIELD

This disclosure relates aqueous polymeric dispersions and to sized carbon fiber tows, and in particular to sized carbon fiber tows with a low concentration of volatile organic compounds (VOC), and methods for preparing the same.

BACKGROUND

In the area of film formation/coating, sizing, industrially adopted incumbent approaches are primarily based on solution impregnation, often restricted by regulatory compliances, which also provides limited/no control over particle size/morphology.

Conventionally used techniques used for producing tailor made ultrafine polymer powders include, for example, mechanical/cryogenic grinding, jet-milling, and precipitation.

Limitations of these approaches include the difficulty of forming regular sized particles with well controlled morphology (in terms of particle size/distribution). Non-uniform particle sized dispersions can lead to poor surface coverage. Additionally, non-uniform appearance/finish can arise due to packing defects during film formation. This can lead to low throughput as well as poor performance of the material.

As an example of the problems associated with some of these techniques for forming powders, grinding, for instance, produces particles with an irregular shape and pointed edges. In current commercial selective laser sintering (SLS) powders, the particle size can vary from 40-60 micrometers and can have potato like morphologies obtained by grinding. To obtain a regular shape and texture, post treatments often need to be carried out to round the pointed edges, thus increasing process cost. Additionally, a sizing application of fiber can necessitate significantly smaller particles/dispersions to ensure optimum impregnation and thermodynamic wet-out. Thus, many techniques in industry produce particles that are too irregularly shaped or too large to be well suited for many applications.

The powders can be formed in dispersions that can be used, for example, in sizing fibers and fiber strands. Sized carbon fibers have enhanced inter-laminar shear strength (ILSS), resulting in improved fiber-matrix adhesion and thereby enhancing the desired properties of composites. Further, sized carbon fibers have improved processability by way of improved fiber bundle cohesion, spreadability, resistance to fuzz formation, fiber smoothness, abrasion resistance, and windability. Thus sizing of reinforcing fibers is a critical step for preparing commercial fiber-reinforced composites.

One key parameter for assessing the quality of sizing is the extent of sizing or the sizing content across a fiber. A uniform sizing content provides the necessary quality of matrix-fiber adhesion, resulting in composites having improved properties. Further, matrix-fiber adhesion and wettability may be further improved by using a sizing agent of the same material as the matrix in which the sized carbon fiber is to be dispersed. With the exponential growth of consumer electronic industry the demand for developing products, which are durable, light-weight and meeting customer aesthetic objectives, are currently more than ever before. Polymer material such as polycarbonates resins is one such material, which meets the criteria and is extensively used in the consumer electronic industry inter alia due to its low weight, high optical transparency, and high impact strength. The possibility of using polycarbonate as a sizing agent has been explored in the past.

The U.S. Pat. No. 4,416,924A (Published Nov. 22, 1983) to Peterson et. al discloses a polycarbonate sizing compositions used for sizing carbon fibers. As disclosed in the patent, organic solvents such as N-methyl-2-pyrrolidone or methylene chloride may be used for dispersing polycarbonate resins to achieve the required dispersion characteristics and sizing quality. However, with increased environmental and product safety regulations, use of organic solvents in sizing compositions are not desirable as even trace amounts in the final composite products may invite regulatory prohibition and severe penalty. As an alternative to organic solvents, aqueous polycarbonate dispersion have been explored for sizing application.

Polycarbonate based aqueous dispersion although desirable in sizing application, has some inherent drawbacks such as non-uniform resin particle size distribution resulting in improper sizing content on the reinforcing fibers. Non-uniform particle sized dispersions can lead to poor surface coverage. Additionally, non-uniform appearance/finish can arise due to packing defects during film/sizing formation. This can lead to low throughput as well as poor performance of the composite product. Sizing application of fiber can necessitate significantly smaller particles/dispersions to ensure optimum impregnation and thermodynamic wet-out.

Giraud et. al in their publication titled “Preparation of aqueous dispersion of thermoplastic sizing agent for carbon fiber by emulsion/solvent evaporation” (Applied Surface Science, Elsevier, 2013, vol. 266, pp. 94-99), discloses the use of thermoplastics such as polyetherimide (PEI) as sizing agent on carbon fibers to obtain sizing, which is environmentally benign as well as uniform on the carbon fiber surface. The publication does not disclose the extent of uniformity of sizing which the PEI sizing provides on the carbon fiber. Further, it will be appreciated that the aqueous dispersion characteristics of PEI will be different from that of a polycarbonate dispersion on account of the different chemical functional/substituent groups present on the polymers leading to a different sizing extent on the carbon fiber surface.

The U.S. Pat. No. 8,314,178 to Terrenoire et. al claims aqueous dispersion of branched polycarbonates for use as papercoating slip. Although the patent discloses the need to keep the concentration of VOC as low as possible in coating/sizing application, the patent does not disclose specific applications to carbon fibers, which would require different processing conditions and dispersion characteristics of the sizing composition.

The U.S. Pat. No. 7,329,696 B2 (Published Feb. 12, 2008) to Ueno et. al discloses an aqueous dispersion of resin particles, which may be of polycarbonate and used for carbon fiber sizing application. The particle size distribution in the sizing composition is such that at least two different size distribution is formed, which would provide less than desired uniformity in sizing content and packing efficiency.

Thus there is a need to develop polycarbonate sized carbon fiber tow, having uniform sizing content and a low concentration of volatile organic compounds with excellent production economics.

SUMMARY OF THE DISCLOSURE

Disclosed herein are aqueous dispersions, methods of making aqueous dispersions, articles comprising elements formed from aqueous dispersions, sized carbon fibers, and methods for making sized carbon fibers.

In an embodiment, an aqueous dispersion can comprise: a plurality of particles each particle comprising a polycarbonate component, wherein individual particles have a D₉₀ in a range of 300 nm to 4,000 nm; a plasticizer component; and a surfactant component.

In an embodiment, a method of forming the aqueous dispersion can comprise: combining an organic phase and an aqueous phase to form a first solution, the organic phase comprising a polycarbonate component and a solvent component, the aqueous phase comprising water and a surfactant component; heating the first solution to evaporate the solvent component; and form a second solution; and combining a plasticizer component with the second solution to form the aqueous dispersion.

In an embodiment, a sized carbon fiber tow can comprise: a polycarbonate sizing on a carbon fiber tow, wherein the polycarbonate sizing has a concentration of volatile organic compounds less than 10 ppm, preferably less than 5 ppm, or less than 2 ppm; and an average sizing content of at least 0.5 wt % of the carbon fiber tow with a coefficient of variation less than 15%, preferably less than 11%.

In an embodiment, a method of preparing the sized carbon fiber tow can comprise: spreading the carbon fiber tow over a spreader unit at a throughput line speed of at least 0.3 meters/minute and forming spread carbon fibers; sizing the spread carbon fibers in a sizing bath containing an aqueous polycarbonate sizing dispersion and forming sized carbon fibers; and drying the sized carbon fibers to obtain the sized carbon fiber tow.

Other features and advantages of the present invention will become apparent from the following figures, detailed description, and examples. It should be understood, however, that the figures, detailed description, and examples, while indicating specific embodiments, are given by way of illustration only and are not meant to be limiting. Additionally, it is contemplated that changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE FIGURES

The drawings illustrate generally, by way of example, but not by way of limitation, various embodiments discussed in the present document.

FIG. 1 is a flow chart of a method of preparing an aqueous dispersion, in accordance with various examples.

FIG. 2 is a schematic diagram showing the formation of the aqueous dispersion, in accordance with various examples.

FIG. 3 is a transmission electron microscopy image showing the aqueous dispersion, in accordance with various examples.

FIG. 4 is a graph showing the dynamic light scattering output of the aqueous dispersion, in accordance with various examples.

FIG. 5 is a Pareto chart showing the effect of various process parameters on the aqueous dispersion, in accordance with various examples.

FIG. 6 is a bar graph showing the minimum film formation temperature of the aqueous dispersion with different amounts of resorcinol diphenyl phosphates included therein, in accordance with various examples.

FIGS. 7A-7C are hot state tapping mode atomic force microscopy images showing the surface roughness of various films formed from the aqueous dispersion, accordance with various examples.

FIG. 8 is an illustration of the overall process flow diagram for carbon fiber sizing and its subsequent application in composites and woven fabrics.

FIG. 9 is a graphical representation of the lowering of coefficient of variation in sizing content based on the results from Example 3.

FIG. 10 is a graphical representation illustrating the lowering of VOC concentration in the sized carbon fiber tow based on the results of Example 3.

DETAILED DESCRIPTION

A potential solution to the problems described herein is to employ an aqueous dispersion that includes a polycarbonate component, a plasticizer component, and a surfactant component. Aqueous dispersions, can deliver stable, small particle sized dispersion (e.g., sub-micrometer scale, controllable by adjusting reagents used in making the aqueous dispersion) with uniform distribution (e.g., monomodal) of particles. This can allow the films, coatings, or powders formed from the aqueous dispersion to have better packing efficiency. Additionally or in the alternative, the plasticizer can impart a low minimum film formation temperature (MFFT) to the aqueous dispersion, which facilitates easy and substantially defect free film formation. Additionally, the aqueous dispersions can be quite stable and show substantially no phase separation. For example, no phase separation is observed for times ranging from one month to several years.

The aqueous dispersion can be used as a sizing composition in preparing a polycarbonate sized carbon fiber tow, having a low concentration of volatile organic compounds and a uniform sizing content across the carbon fiber tow. In particular, the polycarbonate sized carbon fiber can have a concentration of VOC of less than 10 ppm with an average sizing content greater than 0.5 wt % of the carbon fiber tow. The inventors surprisingly found that the sizing content of the carbon fiber tow, is uniform as represented by a coefficient of variation not greater than 15% of the average sizing content. The patent also describes a method of preparing a polycarbonate sized carbon fiber tow using the aqueous polycarbonate dispersion.

In prior art literature, such as the patent EP0546580B1 (Colman et. al), uniformity of coating on a substrate has been expressed using statistical parameters such as coefficient of variation (CoV) of the coating concentration or thickness across a particular substrate. Coefficient of variation is a reliable statistical measure to estimate the variation or deviation of a data set from the average value.

In the present invention, the extent of uniformity of the sizing deposited on the carbon fiber tow is expressed as the coefficient of variation (CoV) of the sizing content across a predetermined length of the sized carbon fiber tow. The predetermined length of the sized carbon fiber tow serves as a sample or representative length to characterize the sizing quality across the sized carbon fiber tow. The predetermined length of the sized carbon fiber tow for sizing content measurement is at least 30 cm, but preferably less than about 100 cm. For example, the predetermined length can be 30 cm. It is observed that at predetermined lengths lower than 30 cm, the weight of the sized carbon fiber tow, is not sufficient to provide an accurate measurement. At predetermined lengths greater than 100 cm, the sizing measurement becomes difficult using the commercially available analytical instruments.

The coefficient of variation (CoV) may be determined from the average sizing content and the standard deviation of the sizing content measured across the predetermined length of the carbon fiber tow. It will be apparent that the sizing content across a particular predetermined length of the sized carbon fiber tow will be lower for a uniformly sized carbon fiber tow as compared to a non-uniform sized carbon fiber tow.

The sizing content of the sized carbon fiber can be measured by ash test or solvent digestion technique (ASTM D2584) depending on the type of sizing agent used and can be calculated as shown below using Formula I. Sizing content is the average sizing content of a carbon fiber measured using the formula:

Sizing content (%)=((w ₁ −w ₀)/w ₀)×100   (Formula I),

wherein, w₁=weight of sized carbon fiber tow; w₀=weight of carbon fiber tow (unsized).

To determine the coefficient of variation in the sizing content both average sizing content and the standard deviation of the sizing content is determined. Using Formula I, the sizing content is measured at various points across the predetermined length of the fiber. Using this data the average value of the sizing content is determined using the formula below: Average Sizing content

x _(a)=(x ₁ +x ₂ + . . . x _(n))/n   (Formula II)

where x₁,x₂,x_(n) represent the sizing content determined using Formula I across a predetermined length of the carbon fiber tow for “n” number of observation. Each observation is made using Formula I for calculating the sizing content. In accordance with one aspect of the present invention, the sizing content of the sized carbon fiber tow is found to be optimum with an average sizing content of at least 0.5 wt % of the carbon fiber tow. Alternatively, the average sizing content of the sized carbon fiber tow is at a range of 0.6 wt % to 3 wt %, preferably at a range of 0.85 wt % to 2.8 wt % and most preferably at a range of 0.95 wt % to 2.4 wt %, of the carbon fiber tow.

The standard deviation may be calculated using the formula

S=[Σ(x _(i) −x _(a))²/(n−1)]^(1/2)   (Formula III)

x_(i) being the result of the i-th measurement of sizing content using Formula I and x_(a) is the average sizing content across the predetermined length of the carbon fiber tow.

The coefficient of variation may be calculated using the formula:

(CoV=S/x _(a))×100   (Formula IV)

where x_(a) is the average sizing content across the predetermined length of the carbon fiber tow and S is the standard deviation of the measured sizing content measured across the predetermined length of the carbon fiber tow. The coefficient of variation (CoV) of the sizing content is found to be less than 15%, preferably less than 12%, and most preferably less than 11%, when measured across a predetermined length of the carbon fiber tow.

The polycarbonate sized carbon fiber tow has low VOC content, is environmentally benign, and complies with regulatory and environmental standards, which are associated with consumer goods. The VOC concentration present in the sized carbon fiber tow is less than 10 ppm, preferably less than 5 ppm, more preferably less than 2 ppm and most preferably less than 1 ppm, as measured using a gas chromatographic technique.

The low VOC concentration of the sized carbon fiber tow is achieved by using an aqueous solvent for dispersing the polycarbonate sizing agent. The need of using environmentally friendly solvents for sizing dispersions has also been discussed by Giraud et. al in their publication where the use of aqueous solvents to disperse the sizing agent has been disclosed. However, without being bound by any theory, it is known that organic solvents provide better dispersion of polymer resins compared to aqueous solvents and hence provide better sizing as compared to aqueous dispersion. It was unexpectedly found that the sizing content on the carbon fiber tow has low concentration of VOC with a uniform sizing content.

An aqueous dispersion can include a plurality of particles suspended and homogenously distributed in an aqueous medium along with a plasticizer and a surfactant. The aqueous dispersion can be well suited for many purposes. For example, the aqueous dispersion can be used to form a film. The film, in turn, can be used to form a sizing on a material such as fiber or a textile. The aqueous dispersion can also be disposed on a surface of a substrate to form a film thereon, which coats the surface.

Additionally, the particles of the aqueous dispersion can be isolated and a powder of the particles can be formed from the isolated particles. For example, the aqueous dispersion can be centrifuged and the supernatant removed from the solid; or the aqueous dispersion can be filtered to provide a filtrate. The solid or filtrate can be washed with deionized water, e.g., one or more times. The washed solid or filtrate can be dried, e.g., under vacuum, to provide the particles.

In the aqueous dispersion, the particles can include a polycarbonate component. Each individual particle of the plurality of particles has substantially the same size and morphology thus, having a monomodal distribution with a narrow dispersion. In some examples, the aqueous suspension can include a second plurality of particles each having the same size and morphology, however, the size and morphology of the second plurality of particles can be different than the first plurality of particles, thus creating a bimodal distribution.

The particles can account for any suitable weight percent (wt %) of the aqueous dispersion. For example, the particles can range from 0.5 wt % of the aqueous dispersion to 90 wt % of the dispersion, 10 wt % to 80 wt %, 20 wt % to 80 wt %, 30 wt % to 70 wt %, or 40 wt % to 60 wt % of the aqueous dispersion. Optionally, the particles can range from 0.5 wt % of the aqueous dispersion to 5 wt % of the aqueous dispersion, 1.5 wt % to 4 wt %, 2 wt % to 3.8 wt %, 2.1 wt % to 2.8 wt % of the aqueous dispersion. At very low concentration of the polycarbonate resin particles, the sizing will not be effective on the carbon fiber tow. At a high concentration, there may be excessive sizing on the carbon fiber tow, which may affect the drapability of the carbon fiber tow. Accordingly, the concentration of the polycarbonate resin particles may be customized as desired.

As described herein, the individual particles can include a polycarbonate component. The polycarbonate component can account for any suitable weight percentage of each particle. For example, the polycarbonate component can range from 50 wt % to 100 wt % of each of the particles, 60 wt % to 100 wt %, 70 wt % to 100 wt %, 80 wt % to 100 wt %, or from 90 wt % to 100 wt % of each of the particles.

Polycarbonates and their methods of manufacture are known in the art, being described, for example, in WO 2013/175448 A1, US 2014/0295363, and WO 2014/072923. Polycarbonates are generally manufactured from bisphenol compounds such as 2,2-bis(4-hydroxyphenyl) propane (“bisphenol-A” or “BPA”), 3,3-bis(4-hydroxyphenyl) phthalimidine, 1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane, or 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane (isophorone), or a combination comprising at least one of the foregoing bisphenol compounds can also be used. In a specific embodiment, the polycarbonate is a homopolymer derived from BPA; a copolymer derived from BPA and another bisphenol or dihydroxy aromatic compound such as resorcinol; or a copolymer derived from BPA and optionally another bisphenol or dihydroxyaromatic compound, and further comprising non-carbonate units, for example aromatic ester units such as resorcinol terephthalate or isophthalate, aromatic-aliphatic ester units based on C₆₋₂₀ aliphatic diacids, polysiloxane units such as polydimethylsiloxane units, or a combination comprising at least one of the foregoing.

“Polycarbonate” as used herein means a polymer or copolymer having repeating structural carbonate units of Formula (I):

wherein at least 60 percent of the total number of R¹ groups are aromatic, or each R¹ contains at least one C₆₋₃₀ aromatic group. Each R¹ group can be the same or different. Specifically, each R¹ can be derived from a dihydroxy compound such as an aromatic dihydroxy compound of Formula (2) or a bisphenol of Formula (3).

In Formula (2), each R^(h) is independently a halogen atom, for example bromine, a C₁₋₁₀ hydrocarbyl group such as a C₁₋₁₀ alkyl, a halogen-substituted C₁₋₁₀ alkyl, a C₆₋₁₀ aryl, or a halogen-substituted C₆₋₁₀ aryl, and n is 0 to 4.

In Formula (3), R^(a) and R^(b) are each independently a halogen, C₁₋₁₂ alkoxy, or C₁₋₁₂ alkyl, and p and q are each independently integers of 0 to 4, such that when p or q is less than 4, the valence of each carbon of the ring is filled by hydrogen. In an embodiment, p and q is each 0, or p and q is each 1, and R^(a) and R^(b) are each a C₁₋₃ alkyl group, specifically methyl, disposed meta to the hydroxy group on each arylene group. X^(a) is a bridging group connecting the two hydroxy-substituted aromatic groups, where the bridging group and the hydroxy substituent of each C₆ arylene group are disposed ortho, meta, or para (specifically para) to each other on the C₆ arylene group, for example, a single bond, —O—, —S—, —S(O)—, —S(O)₂—, —C(O)—, or a C₁₋₁₈ organic group, which can be cyclic or acyclic, aromatic or non-aromatic, and can further comprise heteroatoms such as halogens, oxygen, nitrogen, sulfur, silicon, or phosphorous. For example, X^(a) can be a substituted or unsubstituted C₃₋₁₈ cycloalkylidene; a C₁₋₂₅ alkylidene of the formula —C(R^(c))(R^(d))—wherein R^(c) and R^(d) are each independently hydrogen, C₁₋₁₂ alkyl, C₁₋₁₂ cycloalkyl, C₇₋₁₂ arylalkyl, C₁₋₁₂ heteroalkyl, or cyclic C₇₋₁₂ heteroarylalkyl; or a group of the formula —C(═R^(e))—wherein R^(e) is a divalent C₁₋₁₂ hydrocarbon group.

Some illustrative examples of dihydroxy compounds that can be used include resorcinol, 2,2-bis(4-hydroxyphenyl) propane (“bisphenol A” or “BPA”), 3,3-bis(4-hydroxyphenyl) phthalimidine, 2-phenyl-3,3′-bis(4-hydroxyphenyl) phthalimidine (also known as N-phenyl phenolphthalein bisphenol, “PPPBP”, or 3,3-bis(4-hydroxyphenyl)-2-phenylisoindolin-1-one), 1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane, and 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane (isophorone bisphenol).

In some embodiments, the polycarbonate contains carbonate units (1) and non-carbonate units, for example ester units, polysiloxane units such as polydimethylsiloxane units, or a combination comprising at least one of the foregoing. In some embodiments the ester units can be aromatic ester units (e.g., resorcinol terephthalate or isophthalate), or aromatic-aliphatic esters, based on C₆₋₂₀ aliphatic diacids.

In some embodiments, the polycarbonate is a linear homopolymer containing bisphenol A carbonate units (BPA-PC), commercially available under the trade name LEXAN™ from SABIC™; or a branched, cyanophenol end-capped bisphenol A homopolycarbonate produced via interfacial polymerization, containing 3 mol % 1,1,1-tris(4-hydroxyphenyl)ethane (THPE) branching agent, commercially available under the trade name LEXAN™ CFR from SABIC™. A specific copolycarbonate includes bisphenol A and bulky bisphenol carbonate units, e.g., derived from bisphenols containing at least 12 carbon atoms, for example 12 to 60 carbon atoms or 20 to 40 carbon atoms. Examples of such copolycarbonates include copolycarbonates comprising bisphenol A carbonate units and 2-phenyl-3,3′-bis(4-hydroxyphenyl) phthalimidine carbonate units (a BPA-PPPBP copolymer, commercially available under the trade name LEXAN™ XHT from SABIC™), a copolymer comprising bisphenol A carbonate units and 1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane carbonate units (a BPA-DMBPC copolymer commercially available under the trade name DMX from SABIC™), and a copolymer comprising bisphenol A carbonate units and 1,1-bis(4-hydroxy-3-methylphenyl)-3,3,5-trimethylcyclohexane isophorone bisphenol carbonate units (available, for example, under the trade name APEC from Bayer).

Other specific polycarbonates that can be used include poly(aromatic ester-carbonate)s comprising bisphenol A carbonate units and isophthalate-terephthalate-bisphenol A ester units, also commonly referred to as poly(carbonate-ester)s (PCE) or poly(phthalate-carbonate)s (PPC), depending on the relative ratio of carbonate units and ester units. Another specific poly(ester-carbonate) comprises resorcinol isophthalate and terephthalate units and bisphenol A carbonate units, such as those commercially available under the trade name LEXAN™ SLX from SABIC™.

In another embodiment, the polycarbonate is a poly(carbonate-siloxane) copolymer comprising bisphenol A carbonate units and siloxane units, for example blocks containing 5 to 200 dimethylsiloxane units, such as those commercially available under the trade name LEXAN™ EXL from SABIC™. Other polycarbonates that can be used include poly(ester-siloxane-carbonate)s comprising bisphenol A carbonate units, isophthalate-terephthalate-bisphenol A ester units, and siloxane units, for example blocks containing 5 to 200 dimethylsiloxane units, such as those commercially available under the trade name LEXAN™ FST from SABIC™.

Poly(aliphatic ester-carbonate)s can be used, such as those comprising bisphenol A carbonate units and sebacic acid-bisphenol A ester units, such as those commercially available under the trade name LEXAN™ HFD from SABIC™. Combinations of polycarbonates with other polymers can be used, for example an alloy of bisphenol A polycarbonate with an ester such as poly(butylene terephthalate) or poly(ethylene terephthalate), each of which can be semicrystalline or amorphous. Such combinations are commercially available under the trade name XENOY™ and XYLEX™ from SABIC™.

As described herein, the size of the individual particles can be controlled. Generally, the individual particles have a substantially spherical shape (as is illustrated in FIG. 3) as opposed to an elongated or irregular shape. For example, the individual particles have a generally smooth surface that is substantially free of features such as edges, corners, protrusions, cavities, or the like. The individual particles can have a diameter in the micrometer or nanometer range. The diameter of the individual particles can be governed by the selection of the surfactant component in the aqueous dispersion. In examples, where the particles have a diameter in the micrometer to nanometer range, particles can have a D₉₀ in a range of 300 nm to 4000 nm, 300 nm to 400 nm, 400 nm to 3500 nm, 500 nm to 3000 nm, 600 nm to 2000 nm, 700 nm to 1000 nm, or 800 nm to 900 nm. In some examples, the particles can have a D98 of 340 to 345 nm, e.g., 342 nm.

The aqueous dispersion can include additional components beyond the polycarbonate component. For example, the aqueous dispersion can include a plasticizer (also referred to as coalescing) component. Not to be bound by theory, the plasticizer affects the minimum film formation temperature (MFFT) of the aqueous dispersion by functioning as a coalescing aid to assist film formation. The minimum film formation temperature is the lowest temperature at which the aqueous dispersion will uniformly coalesce when applied on a substrate as a thin film. At a higher temperature the sizing agent may be damaged under the heat and in addition make the overall process energy inefficient. On the other hand, drying below the MFFT will not provide the desired level of dispersion characteristics and the sizing formed would be non-uniform with rough powder like texture on the reinforcing fibers. This in turn would affect the material properties of any composite using such sized reinforcing fibers. An example of a suitable test for determining this temperature involves using a MFFT-Bar, as specified by such standards as ASTM D 2354 and ISO 2115. The design of a potential instrument for testing the MFFT is based on these standards. The plasticizer component can also aid in decreasing the surface tension value of the aqueous dispersion. Depending on the choice of plasticizer, the wettability of the aqueous dispersion can be selectively increased or decreased. Surprisingly, inclusion of the plasticizer component, in the aqueous dispersion leads to substantially no phase separation in the aqueous dispersion.

The plasticizer component can account for any suitable weight percentage of the aqueous dispersion. For example, the plasticizer component can range from 1 wt % to 20 wt % of the aqueous dispersion, 3 wt % to 19 wt %, 4 wt % to 18 wt %, 5 wt % to 17 wt %, 6 wt % to 16 wt %, 7 wt % to 15 wt %, 8 wt % to 14 wt %, 9 wt % to 13 wt %, or 10 wt % to 12 wt % of the total weight of the aqueous dispersion.

The plasticizer component can include one or more plasticizers. Any of the one or more plasticizers can account for any suitable weight percent of the plasticizer component. For example, when two or more plasticizers are present, a plasticizer can range from 50 wt % to 100 wt % of the plasticizer component, 60 wt % to 100 wt %, 70 wt % to 100 wt %, 80 wt % to 100 wt %, or 90 wt % to 100 wt % of the plasticizer component.

The plasticizer of the plasticizer component can include one or more selected from esters, ethers, hydrocarbons, paraffins, sulphonamides, sulfonates, terephthalates, terpenes, and trimellitates. Common among ester-based plasticizers are esters of mono- or di-basic acids such as myristate esters, phthalate esters, adipate esters, phosphate esters, citrates, trimellitates, glutarates, and sebacate esters (e.g., dialkyl phthalates, such as dibutyl phthalate, diisoctyl phthalate, dibutyl adipate, dioctyl adipate; 2-ethylhexyl diphenyl diphosphate; t-butylphenyl diphenyl phosphate; butyl benzylphthalates; dibutoxyethoxyethyl adipate; dibutoxypropoxypropyl adipate; acetyltri-n-butyl citrate; dibutylsebacate; etc.). Phosphate ester plasticizers are commercially sold under the trade designation SANTICIZER™ from Monsanto; St. Louis, Mo. Glutarate plasticizers are commercially sold under the trade designation PLASTHALL™ 7050 from CP. Hall Co.; Chicago, Ill.

Additional examples of ester-based plasticizers include aliphatic monoalkyl esters, aromatic monoalkyl esters, aliphatic polyalkyl esters, aromatic polyalkyl esters, polyalkyl esters of aliphatic alcohols, phosphonic polyalkyl esters, aliphatic poly(alkoxylated) esters, aromatic poly(alkoxylated) esters, poly(alkoxylated) ethers of aliphatic alcohols, and poly(alkoxylated) ethers of phenols. In some embodiments, the esters are derived from an alcohol or from a renewable source, such as 2-octanol, citronellol, dihydrocitronellol or from 2-alkyl alkanols.

The plasticizer can be further chosen from an aliphatic monoalkyl ester, an aromatic monoalkyl ester, an aliphatic polyalkyl ester, an aromatic polyalkyl ester, a polyalkyl ester of an aliphatic alcohol, a phosphonic polyalkyl ester, an aliphatic poly(alkoxylated) ester, an aromatic poly(alkoxylated) ester, a poly(alkoxylated) ether of an aliphatic alcohol, a poly(alkoxylated) ether of a phenol, or mixtures thereof.

Additional examples of plasticizers, which can also have flame retardant features include, organophosphorous compounds such as organic phosphates (including trialkyl phosphates such as triethyl phosphate, tris(2-chloropropyl)phosphate, and triaryl phosphates such as triphenyl phosphate and diphenyl cresyl phosphate, resorcinol bis-diphenylphosphate, resorcinol diphosphate, and aryl phosphate), phosphites (including trialkyl phosphites, triaryl phosphites, and mixed alkyl-aryl phosphites), phosphonates (including diethyl ethyl phosphonate, dimethyl methyl phosphonate), polyphosphates (including melamine polyphosphate, ammonium polyphosphates), polyphosphites, polyphosphonates, phosphinates (including aluminum tris(diethyl phosphinate); halogenated compounds such as chlorendic acid derivatives and chlorinated paraffins; organobromines, such as decabromodiphenyl ether (decaBDE), decabromodiphenyl ethane, polymeric brominated compounds such as brominated polystyrenes, brominated carbonate oligomers (BCGs), brominated epoxy oligomers (BEOs), tetrabromophthalic anyhydride, tetrabromobisphenol A (TBBPA) and hexabromocyclododecane (HBCD); metal hydroxides such as magnesium hydroxide, aluminum hydroxide, cobalt hydroxide, and hydrates of the foregoing metal hydroxide; and combinations thereof. The plasticizer can also be a reactive type compound (including polyols which contain phosphorus groups, 10-(2,5-dihydroxyphenyl)-10H-9-oxa-10-phospha-phenanthrene-10-oxide, phosphorus-containing lactone-modified polyesters, ethylene glycol bis(diphenyl phosphate), neopentylglycol bis(diphenyl phosphate), amine- and hydroxyl-functionalized siloxane oligomers).

The plasticizer can affect the minimum film formation temperature of the aqueous dispersion. The minimum film formation temperature is the lowest temperature at which the aqueous dispersion will uniformly coalesce when applied on a substrate as a film (e.g., a thin film). An example of a suitable test for determining this temperature involves using a MFFT-Bar, as specified by such standards as ASTM D 2354 and ISO 2115. The design of a potential instrument for testing the MFFT is based on these standards. The plasticizer can also decrease the surface tension value of the aqueous dispersion. Depending on the choice of plasticizer, the wettability of the aqueous dispersion can be selectively increased or decreased. Surprisingly, inclusion of the plasticizer in the aqueous dispersion leads to substantially no phase separation in the aqueous dispersion.

In examples of the aqueous dispersion including the plasticizer component, a minimum film formation temperature (MFFT) of the aqueous dispersion can be 100° C. to 180° C., 115° C. to 175° C., 120° C. to 170° C., 125° C. to 165° C., 130° C. to 160° C., 135° C. to 155° C., or 140° C. to 150° C.

The plasticizer can allow for the minimum film formation temperature of the aqueous dispersion to be less than that of a corresponding aqueous dispersion that is free of the plasticizer component. For example, a minimum film formation temperature of the aqueous dispersion can range from 10° C. to 50° C. less than a corresponding aqueous dispersion that is free of the plasticizer component, from 15° C. to 45° C., 20° C. to 40° C., or 25° C. to 35° C. less. The lower minimum film formation temperature of the aqueous dispersion can allow a film to be formed at comparatively lower temperature than the corresponding aqueous dispersion. This can allow for quicker and less costly film formation.

The aqueous dispersion can include additional components beyond the polycarbonate component and the plasticizer component. For example, the aqueous dispersion can include a surfactant component. The surfactant component can be present in an amount of 1 wt % to 20 wt % of the aqueous dispersion, 5 wt % to 15 wt %, or 8 wt % to 12 wt % of the aqueous dispersion.

The surfactant component can include one or more surfactants. When two or more surfactants are present, one surfactant can be 50 wt % to 100 wt % of the surfactant component, 60 wt % to 100 wt %, 70 wt % to 100 wt %, 80 wt % to 100 wt %, or 90 wt % to 100 wt of the surfactant component.

The surfactant(s) can be an anionic surfactant, cationic, or a non-ionic surfactant. Examples of anionic surfactants include stearate sodium, dodecyl sulfate sodium, dodecyl benzene, sulfonate sodium, alginic acid sodium, glycolic acid, ethoxylate 4-tert butylphenyl ether, glycolic acid ethoxylate lauryl ether, glycolic acid ethoxylate 4-nonylphenyl ether, poly(ethylene glycol) 4-nonylphenyl 3-sulfopropyl ether potassium salt, sodium dioctyl sulphosuccinate, ammonium lauryl sulfate, dioctyl sodium sulfosuccinate, perfluorobutane sulfonic acid, perfluorononanoic acid, perfluorooctane sulfonic acid, perfluorooctanoic acid, potassium lauryl sulfate, sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, sodium laureth sulfate, sodium lauroyl sarcosinate, sodium myreth sulfate, sodium pareth sulfate, and sodium stearate or a mixture thereof. Examples of non-ionic surfactants include poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol), poly(ethylene glycol) sorbitan tetraoleate, polyethylene-block-poly(ethylene glycol), sorbitan monopalmitate, polyoxyethylenesorbtan monooleate, or a mixture thereof. Examples of cationic surfactants include benzalkonium chloride, benzethonium chloride, 5-bromo-5-nitro-1,3-dioxane, cetrimonium bromide (cetyl trimethylammonium bromide), cetyl trimethylammonium chloride, dimethyldioctadecylammonium chloride, lauryl methyl gluceth-10 hydroxypropyl dimonium chloride, tetramethylammonium hydroxide, or mixtures thereof.

The class of surfactant can have an impact on the morphology of the particles. One impact the surfactant has on the morphology is that the particles have a substantially spherical shape in a monomodal or bimodal distribution. The diameter of each particle can additionally be controlled. For example, if the surfactant is anionic then the particles will be monomodal in distribution with a diameter in the nanometer range. Alternatively, if the surfactant is nonionic then the particles will be monomodal in distribution with a diameter in the micrometer range. A mixture of anionic and nonionic surfactants in the aqueous dispersion can lead to a bimodal distribution of particles with a nanometer diameter and particles with a micrometer distribution. Although in this instance, the substantial majority (e.g., 98 vol %) of the particles will have a diameter in the nanometer range.

Various additional components and additives can be present in the aqueous dispersion. For example, a solvent such as dichloromethane, chloroform, demethylformamide, dimethyl sulfate, tetrahydrofuran, or mixtures thereof can be present in the aqueous dispersion. The solvent is selected to dissolve the polymer to the desired degree as described below; to have a boiling point less than water under the process conditions of forming the particles; and to be sufficiently immiscible with water to form a solution with water.

Additional additive(s) that can be present in the aqueous dispersion include a particulate filler, an antioxidant, a heat stabilizer, a light stabilizer, an ultraviolet light stabilizer, an ultraviolet absorbing additive, a non-infrared absorbing additive, an infrared absorbing additive, a lubricant, a release agent, an antistatic agent, an anti-fog agent, an antimicrobial agent, a colorant, a laser marking additive, a surface effect additive, a radiation stabilizer, an anti-drip agent, a fragrance, a fiber, a flow promoter, or a mixture thereof. Examples of suitable flow promoters include an unmodified fumed metal oxide, a hydrophobic fumed metal oxide, a hydrophilic fumed metal oxide, hydrated silica, amorphous alumina, glassy silica, glassy phosphate, glassy borate, glassy oxide, titania, talc, mica, kaolin, attapulgite, calcium silicate, magnesium silicate, or a mixture thereof.

One non-limiting benefit that can be realized with the instant aqueous dispersion is that when the polycarbonate component, surfactant component, and plasticizer component are present, in the disclosed amounts, the aqueous dispersion shows good stability. For example, in dispersions, which include 1 wt % to 20 wt % plasticizer, substantially no phase separation has been visually observed in dispersions for a period of time exceeding one month. For example no visible phase separation occurs in aqueous dispersions having a particle size ranging from 300 nanometers to 4000 nanometers for a period of time of at least 5 days, for example, at least 15 days, at least 45 days, at least two months, at least 6 months, at least 8 months, at least 12 months, and even at least 18 months.

Various articles can be produced from the aqueous dispersion. For example, the aqueous dispersion can form a sizing, powder, a film, a coating, a tie layer, an adhesive, a composite unidirectional tape, or a three-dimensional printed article. In some examples, a tie layer formed from the aqueous dispersion bonds a metal to a fluoropolymer, a powder coating, or an epoxy-toughening coating.

Additionally, the aqueous dispersion can be applied to a fiber such as glass fibers, carbon fibers, aramid fibers, polyethylene fibers, polyester fibers, polyamide fibers, ceramic fibers, basalt fibers, steel fibers, and/or the like. Carbon fibers or fiber strands can be used. The strand of fibers can include, e.g., between 250 and 610,000 fibers (e.g., 1K, 3K, 6K, 12K, 24K, or larger strands can be used).

As an example, sizing is a process in which fibers are coated with a material in order to protect the fibers from damage (e.g., splitting) during processing and to enhance adhesion between the fibers and materials that are subsequently applied to the fibers. As an example, sizing is performed at least by contacting fibers from a strand of fibers with the aqueous dispersion. Such contacting can be performed by immersing the fibers in the dispersion, cascading the dispersion onto the fibers, brushing the dispersion onto the fibers, or spraying the dispersion onto the fibers. Once sized with the dispersion, such fibers can be disposed around a spool (e.g., in the form of a strand) for later use in making fiber tapes or laminates. In some examples, such fibers can be woven into textiles and/or fabrics thus the aqueous dispersion can be part of a woven.

FIG. 1 illustrates a general process flow diagram for preparing sized carbon fiber tow. Optionally, the sizing process can be initiated by unspooling a spool of unsized carbon fiber tow, e.g., procured from a supplier. For example, a spool of unsized carbon fiber tow is unspooled over a bobbin prior to spreading the carbon fiber tow. Alternatively, the carbon fiber tow may be used directly by integrating the sizing line with a pre-sizing treatment unit without winding or unspooling the carbon fibers separately (e.g., the fibers can be sized directly without having been wound on a spool).

The unsized surface-treated carbon fiber tow may have carbon fiber filament number from 1000 (1K) to 50,000 (50K) filaments. The carbon fiber filaments may have a diameter in a range of about 1 micrometer (μm) to about 12 μm, preferably in the range of about 3 μm to about 10 μm, and most preferably in the range of about 5 μm to about 8 μm. For example, a carbon fiber tow having filament number of 12K may be used. The carbon fiber filaments can be derived from polyacrylonitrile (PAN) although other sources such as pitch, rayon, polyesters, polyamides, may also be used as a source for the carbon fiber filaments. The carbon fiber filaments may be optionally electrolytically surface-treated prior to commencing the sizing process as disclosed in the U.S. Pat. No. 4,234,398. Surface treatment or surface functionalization of the carbon fiber filaments introduces polar functional groups on the carbon fiber surface, which enhances the surface energy of the carbon fibers, which in turn helps in improving the adhesion or wettability of fibers with a resin matrix in composites.

One of the ways of achieving an optimum level of sizing on carbon fibers is to spread the unspooled carbon fibers to an optimum level of spreadability prior to applying the sizing agent. An optimum level of spreadability ensures excellent resin impregnation resulting in improved resistance to delamination and improved mechanical properties in composite products. The carbon fiber tow after unspooling can be drawn towards a spreader unit at a specific throughput line speed to generate spread carbon fibers. The spreading unit can comprise at least five rollers, preferably at least six rollers, and most preferably at least seven rollers, over which the spread carbon fibers are processed. Carbon fiber path in the spreading unit can have a total wrapping angle of at least 500 degrees and preferably at least 506 degrees. The sizing equipment can have a tension controlled creel system from which a carbon fiber tow is dispatched and passed over to the spreader unit for spreading the carbon fiber tow. The sizing equipment tension may be kept at a range of about 0.5 Newtons (N) to about 5 N for drawing the carbon fibers. For example, the sizing equipment tension can be kept at 1N.

The sizing process should to take place within a specific range of throughput line speed for ensuring excellent sizing content and process productivity. The spreading and sizing of the carbon fibers can be carried out at a throughput line speed of at least 0.3 meter/minute, preferably a throughput line speed of 0.4 meters/minute to 2 meter/minute, and most preferably at 0.8 meter/minute to 1.2 meter/minute.

Spreadability of the carbon fiber may be calculated by using Formula V. The spreadability value of the carbon fibers when measured in accordance with Formula V is at least 150%, preferably in a range of 155% to 220%, and most preferably in a range of 178% to 202%.

Spreadability (%)=((Sb−Sa)/(Sa))×100   (Formula V)

wherein: Sb=final width of carbon fiber tow emerging from the spreader unit before sizing; and

Sa=width of the unsized carbon fiber before entering the spreader unit.

The spread carbon fibers from the spreader unit, can be drawn to a sizing bath containing the aqueous polymer dispersion (e.g., the aqueous polycarbonate sizing dispersion), for sizing the spread carbon fibers to form sized carbon fibers. The dispersion can be maintained at an ambient room temperature. The sizing can be carried out at a throughput line speed of at least 0.3 meter/minute, preferably at 0.4 meter/minute to 2 meter/minute, and most preferably at 0.8 meter/minute to 1.2 meter/minute.

The sized carbon fibers obtained from the sizing bath, may be subsequently passed through a nip roller to squeeze out any excess aqueous dispersion on the carbon fiber surface before drying the fibers (e.g., in an oven) to obtain the sized carbon fiber tow. It has been observed that the drying of the sized carbon fibers should to be conducted at a raised temperature. At too low a temperature, the drying is ineffective while at very high temperature the sizing may get degraded. The oven used for drying can be maintained at a temperature range of 150° C. to 300° C. and preferably in a range of 200° C. to 270° C., and most preferably in a range of 200° C. to 270° C. The sized carbon fiber tow may be subsequently wound on a spool, e.g., by a take-up winder, to be transported to a different location for further processing. Alternatively, the sized carbon fiber tow can be directly passed to a production line for composite manufacturing or for further processing, e.g., using an integrated production line.

The aqueous dispersion can be formed through various methods. An example of a method of forming the aqueous dispersion includes combining an organic phase and an aqueous phase to form an emulsification composition. The organic phase includes the polycarbonate component and the solvent component. The aqueous phase includes water and the surfactant component. The organic phase or the aqueous phase can include other components such as plasticizers or other additives.

The organic phase and the aqueous phase are added slowly to each other (e.g., drop-wise). Once the organic phase and aqueous phase are combined, the solution is formed. The solution is formed at this stage with a homogenizer. The homogenizer is able to mix the emulsification composition under high shear, e.g., ranging from 7,000 to 30,000 rpm or from 15,000 to 25,000 rpm. The homogenizer operates for a time ranging from 2 to 40 minutes or from 8 to 30 minutes.

Once the solution is formed it is heated to a temperature sufficient to remove the solvent. The solvent then evaporates leaving the aqueous dispersion of particles, surfactant, plasticizer, and other optional additives.

EXAMPLES

Various embodiments of the present disclosure can be better understood by reference to the following Examples which are offered by way of illustration. The present disclosure is not limited to the Examples given herein.

Example 1.1 Preparation of Aqueous Polycarbonate Dispersion

TABLE 1 Materials Aromatic Polycarbonate Bisphenol A-PC (BPA-PC), MW 21,800 Dichloromethane (DCM) AOT 70 PG (Sodium dioctyl sulphosuccinate in mixture of propylene glycol and water) TWEEN-80 (Polyoxyethylenesorbitan monooleate) Tween 15-S-9 (a secondary alcohol ethoxylate) Cremophor 25 (a ceteareth-25) TMN-10 (a branched secondary alcohol ethoxylate) Triton X-45 (an octylphenol ethoxylate) TNP-40 (a nonylphenol ethoxylate) Deionized water Resorcinol Diphenyl Phosphate (RDP) as a plasticizer component

In a glass beaker 5 wt % aromatic polycarbonate BPA-PC was dissolved in DCM at room temperature. Five wt % surfactant (with respect to polymer concentration), dissolved in deionized (DI) water was added drop by drop in PC/DCM solution with intensive stirring (3000 RPM) using an IKA Ultraturrax T25 homogenizer. The mixture was subsequently stirred at 20000 RPM for 10 min to form Dispersion-I.

Dispersion-I was then transferred dropwise to a receiving vessel containing the surfactant/water mixture at 5 wt % surfactant with respect to the polymer concentration and maintained at a temperature of 75° C. for 30 min. After complete transfer, the receiving vessel was held at ˜80° C. for 10 minutes (with continuous stirring) to remove most of the organic solvent, leading to final PC dispersion with trace amount of residual DCM (ppm level).

FIG. 1 is a flow chart of the process, and FIG. 2 is a schematic diagram of a possible mechanism of forming the aqueous dispersion. High shear mixing of PC polymer in solvent and de-ionized water with surfactant produces emulsion droplets dispersed in water. The surfactant with polar and non-polar ends protects these emulsion droplets from coalescing. Solution or Dispersion-I (before DCM removal) leads to the formation of droplets with wide distribution, and phase separation observed after 1 day. During a subsequent distillation process, DCM dissolved in the water is removed, while DCM from inside the droplets evaporates into the water. It has been observed that droplets with wide distribution throughout the dispersion are formed through this emulsification process.

The diffusion of solvent from the droplet causes shrinkage of the droplets and it can be seen that greater than (>) 80% shrinkage occurs when all the solvent is driven out of the droplet (no phase separation observed for >1 month).

PC dispersion morphology (particle size/shape/distribution etc.) developed by the method could be fine-tuned by changing recipe/process parameters.

Example 1.2 Influence of Surfactant on Particle Size and Particle Size Distribution

The resultant product, as prepared by the process described herein, gives stable polycarbonate aqueous dispersions (no phase separation, monitored over >1 month), with 100% conversion (no left over residue). Particle size and distributions were controlled by changing choice of surfactant and their composition Table 1). Anionic surfactant AOT 70 PG provides submicron sized particles in dispersion whereas nonionic TWEEN 80 leads to micron sized particles, both with monomodal particle size distributions. A combination of the above two surfactants leads to bimodal distributions, with a combination of smaller (sub-micron sized) and bigger (micron sized) ones.

TABLE 2 Reagent amounts in PC dispersion forming experiments Organic/ Particle Surfactant Polymer Water Anionic/ size, DLS, Particle size Surfactant conc., % conc., % ratio Ionic ratio nm distribution AOT 70 PG 10 5 0.5 NA  342, 100% Monomodal (Anionic) TWEEN 80 10 5 0.5 NA 3282, 100% Monomodal (Nonionic) Mixed 10 5 0.5 2.33 462, 98%; Bimodal (AOT 70PG/ 4520, 2% TWEEN 80, 70/30) Shear time 30 min Shear rate, RPM 20000K

Particle size of submicron PC dispersions in dry/wet form were analyzed by transmission electron microscopy (TEM), as illustrated in FIG. 3 and dynamic light scattering experiments (DLS), as illustrated in FIG. 4.

Dynamic light scattering experiments were carried out using a Malvern Nanosizer ZS. The polycarbonate aqueous dispersion samples were analyzed in a disposable cuvette with 5% polycarbonate aqueous dispersion, further diluting by 50% with DI water, at 20° C. The angle of detection of the scattered light was 173°, as determined by back-scatter. The Nanosizer ZS used a 4 mW He—Ne laser, with an operating wavelength (λ0) of 633 nm.

Dynamic light scattering experiments probe the Brownian motion of the particles in a liquid suspension under conditions of constant temperature. The Stokes-Einstein relation, represented by Equation 1, relates the hydrodynamic diameter and translational diffusion coefficient.

$\begin{matrix} {D = \frac{kT}{6{\pi\eta}\; A}} & (1) \end{matrix}$

In Equation 1, D is the translational diffusion coefficient, k is the Boltzmann constant, T is the temperature in degrees Celsius (° C.), and η is the liquid viscosity

For the dynamic light scattering study, particle size distribution for all polycarbonate aqueous dispersion samples were derived solely from the intensity particle size distribution.

Example 1.4 Phase Separation Analysis

Aqueous dispersions were analyzed for visible phase separation. A solution was considered to show visible phase separation when the polycarbonate particles were agglomerated or a distinct aqueous and organic phase were present. Samples were stored at room temperature. As shown in Tables 3 and 4, samples including polycarbonate particles having a monomodal distribution of particles not exceeding 4000 nanometers in size showed no phase separation after 60 days of storage. In contrast, aqueous dispersions having a bimodal distribution of polycarbonate particle or polycarbonate particles exceeding a size of 4000 nanometers showed visible phase separation after 15 days of storage.

TABLE 3 Phase separation of aqueous dispersions having polycarbonate particles with sizes less than 4000 nm. Phase Separation Particle Size, nm Particle Size Distribution Observed, if any Surfactant Day 1 Day 15 Day 30 Day 45 Day 1 Day 15 Day 30 Day 45 Day 60 AOT 70PG 342 342 340 342 100% 100% 100% 100% No (Anionic) Monomodal Monomodal Monomodal Monomodal TWEEN 80 3282 3282 3281 3283 100% 100% 100% 100% No (Nonionic) Monomodal Monomodal Monomodal Monomodal Mixed AOT 462, 98%; 462, 98% 460, 95% 480, 95% Bimodal Bimodal Bimodal Bimodal Yes 70PG/TWEEN 4520, 2% 4550, 2% 4525, 5% 4580, 5% 80: 70/30

TABLE 4 Phase separation of aqueous dispersions having polycarbonate particles with sizes greater than 4000 nm. Particle size of Dispersion (nm) Surfactant Day 1 Day 15 Tween 15-S-9 5500 80%; 640 20% Phase separation observed Cremophor 25 4230 85%; 450 15% Phase separation observed TMN-10 5290 65%; 550 35% Phase separation observed Triton X-45 4110 80%; 350 20% Phase separation observed TNP-40 4980 55%; 750 45% Phase separation observed

Example 1.4 Statistical Analysis

Statistical analysis was executed to understand the effect of process parameters (with respect to polymer concentration, organic/water ratio, surfactant concentration, composition etc.) on dispersion quality by examining the factorial design with a JMP software product. Pareto charts (FIG. 5) showed the statistical significance of each effect as a measure of its standardized effect. Examples of process parameters are:

-   -   Low polymer concentration;     -   Low organic/water ratio;     -   Surfactant concentration; and     -   Anionic/nonionic surfactant ratio.

Example 1.5 Film Formation From Dispersions

Minimum film formation temperature gradient plate (MFFT) was used to analyze the effect of particle size on film formation behavior of aqueous PC dispersions. In emulsion systems, an unbroken film formed when the polymer particles became coalesced, which ensured effective diffusion of polymer chains across the particle boundary, hence, ensuring production of films with enhanced performance.

It was observed that sub-micrometer scaled aqueous PC dispersions impart lower MFFT values compared to micronized ones. This could be because of differences in degrees of water plasticization. Water plasticizes the smaller particle size to a greater extent (high surface to volume ratio), hence enabling easier film formation. However, challenges observed in terms of film continuity; as developed in nanoscale PC dispersions showed poor wettability/broken film formation when applied on fibers.

Flame retardant additive resorcinol diphenyl phosphate (RDP) was identified as a coalescing aid for the PC dispersion which could reduce the MFFT value by >10° C., without affecting resin properties (FIG. 6). Improved flowability and plasticizing effect in presence of RDP was also corroborated by hot stage tapping mode atomic force microscopy (TM-AFM) study (FIGS. 7A-7C). Neat PC dispersion (without additive) reveals scattered particles at the same temperature with no change in surface roughness value PC dispersion (FIG. 7A). Neat PC dispersion reveals scattered particles heated to 130° C. shows a surface roughness of 0.05 micron (FIG. 7B). PC with 15 wt % RDP shows film formation, along with lowering in surface roughness (0.06 micron to 0.012 micron) when heated at 130° C. (FIG. 7C), indicating, in part, a homogenous distribution of the polycarbonates.

Example 2: Preparing Aqueous Polymer Dispersion

Process/Procedure: FIG. 8 is a flow chart of the overall sizing process. Polycarbonate dispersions of concentrations of 3.5, 2.5, 2.1 and 1.6 wt % were prepared in accordance with Example 1.1. Flame retardant additive resorcinol diphenyl phosphate (RDP) was identified as a coalescing aid for the PC dispersion, which was introduced to the aqueous polycarbonate dispersion so obtained. The RDP added may be 15 wt % of the aqueous sizing dispersion.

Example 3: Sizing Process and Characterization of Sized Carbon Fiber Tow

Purpose: Example 3 demonstrates an embodiment of the present invention where polycarbonate sized carbon fiber tow are prepared using the aqueous polycarbonate dispersion prepared as described under Example 2. The example further demonstrates the superior sizing content uniformity across the carbon fiber tow in addition to the low VOC concentration.

Material used: A fiber sizing line fabricated by Izumi International, USA was custom designed.

Process/Procedure: The polycarbonate dispersions were prepared at concentrations of 3.5, 2.5, 2.1, 1.6 wt % as described under Example 2. A carbon fiber tow was unspooled over a bobbin and was subsequently spread using a spreader unit to generate spread carbon fibers at a line speed of 1 m/min. The spread carbon fibers were passed through a sizing bath containing the aqueous polycarbonate sizing dispersion at a line speed of 1 m/min and sized carbon fibers were obtained. The sizing dispersion was stirred continuously with a stirrer for homogenization during the experiment. The sized carbon fibers was then passed through heaters for drying to obtain the sized carbon fiber tow. The sized carbon fibers may be passed to the nip roller where excess sizing solution was taken out. The sized carbon fiber tow was subsequently wounded around winder to be utilized for making composite products. Headspace Gas Chromatography method was used for quantifying dichloromethane (DCM) content in the sized carbon fiber tow. The dichloromethane was quantified using Flame Ionization Detector (FID). The process was repeated for each set of control to prepare the sized carbon fiber tow for further analysis.

Operating Parameters: The sizing processing parameters have been illustrated below as given.

TABLE 5 Operating parameters for sizing Values PC content as a % of dispersion Operating Parameters 3.5 2.5 2.1 1.6 Line speed 1 m/min Line tension 1N Stirrer speed 300 rpm Temperature of sizing bath Ambient Room temperature Temperature IR heater 250 deg C. Temperature of oven 250 deg C. Winder speed 1 m/min Head Space Chromatography Oven temperature 120° C. Loop temperature 130° C. Transfer line temperature 135° C. Vial equilibration time 30 min GC cycle time 25 min Column CP-wax-52 CB Column oven temperature 40° C. (2 min)-200° C. (2 min, 10° C./min) Inlet temperature 250° C. FID temperature 300° C.

Results: The results of the experiment have been disclosed as below:

TABLE 6 Characterization of sized carbon fiber tow Std. Average deviation PC emulsion in Solvent Sizing at 30 cm VOC Experiment Sizing bath used Content % of fiber CoV Content Experiment 2 2.5% solid content Aqueous + 1.698 0.167 9.8 <2 RDP Comparative Ex 2a 2.5% solid content DCM 4.1 0.155 3.7 60 Comparative Ex 2b 2.5% solid content Aqueous 1.74 0.315 18.1 <2 Experiment 3 2.1% solid content Aqueous + 1.261 0.128 10.6 <2 RDP Comparative Ex 3a 2.1% solid content DCM 3.2 0.124 3.9 40 Comparative Ex 3b 2.1% solid content Aqueous 1.316 0.213 16.2 <2 Experiment 4 1.6% solid content Aqueous + 1.01 0.105 10.4 <2 RDP Comparative Ex 4a 1.6% solid content DCM 2.5 0.101 4.1 15 Comparative Ex 4b 1.6% solid content Aqueous 1.06 0.176 16.6 <2 Experiment 5 3.5% solid content Aqueous + 2.35 0.242 10.3 <2 RDP Comparative Ex 5a 3.5% solid content DCM 6.7 0.197 2.9 115 Comparative Ex 5b 3.5% solid content Aqueous 2.44 0.45 18.4 <2

As observed on the basis of the experimental results from Table 6 above, carbon fiber tow sized with the polycarbonate aqueous dispersions of the present invention containing plasticizer component RDP, has a lower coefficient of variation of sizing content compared to the corresponding carbon fiber tow prepared with aqueous sizing dispersion of polycarbonate having no plasticizer component. The coefficient of variation of sizing content of the sized carbon fiber tow developed in the present embodiment of the invention, was at least 33% lower compared to the sizing content of carbon fiber tow prepared using conventional polycarbonate aqueous dispersion without RDP. Thus indicating more uniformity in the sizing content for carbon fiber tow developed. Further, sized carbon fiber tow of the present embodiment of the invention prepared with polycarbonate aqueous dispersion containing the RDP as plasticizer component has a significantly lower VOC content. As observed VOC concentration of the sized carbon fiber tow developed in the present embodiment of the invention was as at least 95% lower than polycarbonate sized carbon fiber tow prepared with conventional dispersion of polycarbonate in DCM.

Result from Example 3 as an embodiment of the present invention, demonstrate that polycarbonate sized carbon fiber tow of the present invention has excellent uniformity in sizing content along with low VOC concentration compared to conventional polycarbonate sized carbon fiber tow. FIG. 9 and FIG. 10 provides a graphical representation of the lowering of coefficient of variation and VOC concentration in the sized carbon fiber tow. The sized carbon fiber tow, as shown, complies with the requirement of having low concentration of VOC with excellent sizing content with the desired uniformity in the sizing content.

The terms and expressions that have been employed are used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the embodiments of the present disclosure. Thus, it should be understood that although the present disclosure has been specifically disclosed by specific embodiments and optional features, modification and variation of the concepts herein disclosed may be resorted to by those of ordinary skill in the art, and that such modifications and variations are considered to be within the scope of embodiments of the present disclosure.

Throughout this document, values expressed in a range format should be interpreted in a flexible manner to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. For example, a range of “about 0.1% to 5%” or “about 0.1% to 5%” should be interpreted to include not just 0.1% to 5%, but also the individual values (e.g., 1%, 2%, 3%, and 4%) and the sub-ranges (e.g., 0.1% to 0.5%, 1.1% to 2.2%, 3.3% to 4.4%) within the indicated range. The statement “about X to Y” has the same meaning as “about X to Y,” unless indicated otherwise. Likewise, the statement “about X, Y, or Z” has the same meaning as “about X, Y, or Z,” unless indicated otherwise.

The compositions, methods, and articles can alternatively comprise, consist of, or consist essentially of, any appropriate materials, steps, or components herein disclosed. The compositions, methods, and articles can additionally, or alternatively, be formulated so as to be devoid, or substantially free, of any materials (or species), steps, or components, that are otherwise not necessary to the achievement of the function or objectives of the compositions, methods, and articles.

In this document, the terms “a,” “an,” or “the” are used to include one or more than one unless the context clearly dictates otherwise. The term “or” is used to refer to a nonexclusive “or” unless otherwise indicated. The statement “at least one of A and B” has the same meaning as “A, B, or A and B.” In addition, it is to be understood that the phraseology or terminology employed herein, and not otherwise defined, is for the purpose of description only and not of limitation. Any use of section headings is intended to aid reading of the document and is not to be interpreted as limiting; information that is relevant to a section heading may occur within or outside of that particular section.

In the methods described herein, the acts can be carried out in any order without departing from the principles of the disclosure, except when a temporal or operational sequence is explicitly recited. Furthermore, specified acts can be carried out concurrently unless explicit claim language recites that they be carried out separately. For example, a claimed act of doing X and a claimed act of doing Y can be conducted simultaneously within a single operation, and the resulting process will fall within the literal scope of the claimed process.

Unless specified to the contrary herein, all test standards, including ISO and ASTM, are the most recent standard in effect as of Aug. 1, 2017.

All cited patents, patent applications, and other references are incorporated herein by reference in their entirety. However, if a term in the present application contradicts or conflicts with a term in the incorporated reference, the term from the present application takes precedence over the conflicting term from the incorporated reference

The term “substantially” as used herein refers to a majority of, or mostly, as in at least 50%, 60%, 70%, 80%, 90%, 95%, 96%, 97%, 98%, 99%, 99.5%, 99.9%, 99.99%, or at least 99.999% or more, or 100%.

The term “solvent” as used herein refers to a liquid that can dissolve a solid, liquid, or gas. Non-limiting examples of solvents are silicones, organic compounds, water, alcohols, ionic liquids, and supercritical fluids.

As used herein, the term “polymer” refers to a molecule having at least one repeating unit and can include copolymers.

The polymers described herein can terminate in any suitable way. In some embodiments, the polymers can terminate with an end group that is independently chosen from a suitable polymerization initiator, —H, —OH, a substituted or unsubstituted (C₁-C₂₀)hydrocarbyl (e.g., (C₁-C₁₀)alkyl or (C₆-C₂₀)aryl) interrupted with 0, 1, 2, or 3 groups independently selected from —O—, substituted or unsubstituted —NH—, and —S—, a poly(substituted or unsubstituted (C₁-C₂₀)hydrocarbyloxy), and a poly(substituted or unsubstituted (C₁-C₂₀)hydrocarbylamino).

The term “substituted” as used herein in conjunction with a molecule or an organic group as defined herein refers to the state in which one or more hydrogen atoms contained therein are replaced by one or more non-hydrogen atoms. The term “functional group” or “substituent” as used herein refers to a group that can be or is substituted onto a molecule or onto an organic group. Examples of substituents or functional groups include, but are not limited to, a halogen (e.g., F, Cl, Br, and I); an oxygen atom. Non-limiting examples of substituents that can be bonded to a substituted carbon (or other) atom include F, Cl, Br, I, OR, OC(O)N(R)₂, CN, NO, NO₂, ONO₂, azido, CF₃, OCF₃, R, O (oxo), S (thiono), C(O), S(O), methylenedioxy, ethylenedioxy, N(R)₂, SR, SOR, SO₂R, SO₂N(R)₂, SO₃R, C(O)R, C(O)C(O)R, C(O)CH₂C(O)R, C(S)R, C(O)OR, OC(O)R, C(O)N(R)₂, OC(O)N(R)₂, C(S)N(R)₂, (CH₂)₀₋₂N(R)N(R)₂, N(R)N(R)C(O)R, N(R)N(R)C(O)OR, N(R)N(R)CON(R)₂, N(R)SO₂R, N(R)SO₂N(R)₂, N(R)C(O)OR, N(R)C(O)R, N(R)C(S)R, N(R)C(O)N(R)₂, N(R)C(S)N(R)₂, N(COR)COR, N(OR)R, C(═NH)N(R)₂, C(O)N(OR)R, and C(═NOR)R, wherein R can be hydrogen or a carbon-based moiety; for example, R can be hydrogen, (C₁-C₄₀)hydrocarbyl, alkyl, aryl, or wherein two R groups bonded to a nitrogen atom or to adjacent nitrogen atoms can together with the nitrogen atom or atoms form a heterocyclyl.

The term “alkyl” as used herein refers to straight chain and branched alkyl groups and cycloalkyl groups having from 1 to 40 carbon atoms, 1 to 20 carbon atoms, 1 to 12 carbons or, in some embodiments, from 1 to 8 carbon atoms. Examples of straight chain alkyl groups include those with from 1 to 8 carbon atoms such as methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, and n-octyl groups. Examples of branched alkyl groups include, but are not limited to, isopropyl, iso-butyl, sec-butyl, t-butyl, neopentyl, isopentyl, and 2,2-dimethylpropyl groups. As used herein, the term “alkyl” encompasses n-alkyl, isoalkyl, and anteisoalkyl groups as well as other branched chain forms of alkyl. Representative substituted alkyl groups can be substituted one or more times with any of the groups listed herein, for example, amino, hydroxy, cyano, carboxy, nitro, thio, alkoxy, and halogen groups.

The term “aryl” as used herein refers to cyclic aromatic hydrocarbon groups that do not contain heteroatoms in the ring. Thus aryl groups include, but are not limited to, phenyl, azulenyl, heptalenyl, biphenyl, indacenyl, fluorenyl, phenanthrenyl, triphenylenyl, pyrenyl, naphthacenyl, chrysenyl, biphenylenyl, anthracenyl, and naphthyl groups. In some embodiments, aryl groups contain 6 to 14 carbons in the ring portions of the groups. Aryl groups can be unsubstituted or substituted, as defined herein. Representative substituted aryl groups can be mono-substituted or substituted more than once, such as, but not limited to, a phenyl group substituted at any one or more of 2-, 3-, 4-, 5-, or 6-positions of the phenyl ring, or a naphthyl group substituted at any one or more of 2- to 8-positions thereof.

The term, “anionic surfactant” as used herein refers to anionic surfactants and zwitterionic or amphoteric surfactants which have an attached group that is anionic at the pH of the composition, or a combination thereof.

The total amount of components always totals 100 wt %. Therefore, the components of the aqueous dispersion total 100 wt %.

The term “D₉₀” as used herein refers to the value of the particle diameter at 90% of the cumulative distribution of particles as determined by analyses of a dynamic light scattering plot. As an example if D₉₀=X nm, then 90% of the particles are have a diameter of X nm or less.

The term “D₉₈” as used herein refers to the value of the particle diameter at 98% of the cumulative distribution of particles as determined by analyses of a dynamic light scattering plot. As an example if D₉₈=X nm, then 98% of the particles are have a diameter of X nm or less.

The term “emulsion” as used herein refers to a heterogeneous system of at least two immiscible liquids.

The term “dispersion” as used herein refers to a suspension including solid particles.

The term “tow” means a bundle of carbon fibers comprising several thousand individual carbon fiber filaments bundled together in the form of a spool, which may be transported and handled for further processing.

The term “throughput line speed” means the speed at which the bobbins or spool or rollers, are rotated or operated at for drawing the carbon fiber filaments for sizing or spreading.

The term “plasticizer” means a compound, which helps in coalescing the polymer particles of the sizing composition to form a uniform sizing on the reinforcing carbon fiber and helps in reducing the minimum film forming temperature (MFFT) to form the sizing.

Minimum Film Forming Temperature (MFFT) is the temperature required to uniformly coalesce a sizing agent on the carbon fiber surface.

The term “drapability” or “drape” means flexibility or the bending ability of the sized fiber over a bobbin or a roller.

The term “carbon fiber tow” means a bundle of carbon fiber filaments without sizing.

The term “sized carbon fiber” means a bundle of carbon fiber filaments having polymeric coating on the surface of carbon fibers after dip-coating the carbon fiber in a sizing bath followed by drying.

The term “sizing content” means the extent of sizing or the amount of sizing or coating deposited on the carbon fiber tow surface expressed as a percentage weight of the unsized carbon fiber tow.

The term “volatile organic compounds” or “VOC” means organic solvents having low boiling point preferably lower than that of water and generally used for dissolving polymer resins.

The term “substantially free of volatile organic compounds” means that the concentration of volatile organic compounds is less than 10 ppm.

The term “bobbin” or “spool” means individual package comprising a carbon fiber roving which, is wound on to a core/support.

The term “wrapping angle” means the distance in degrees that the tensioned carbon fiber contacts the roller pins.

The term “ppm” means concentration of a substance expressed as parts per million by weight or the concentration of one part of a substance out of a million part of the total system in which the substance is present.

The following aspects are provided, the numbering of which is not to be construed as designating levels of importance:

Aspect 1 provides an aqueous dispersion comprising: a plurality of particles each particle comprising a polycarbonate component, wherein individual particles have a D90 in a range of 300 nm to 4000 nm; a plasticizer component; and a surfactant component.

Aspect 2 provides the aqueous dispersion of Aspect 1, wherein the particles range from 5 wt % of the aqueous dispersion to 90 wt % of the dispersion.

Aspect 3 provides the aqueous dispersion according to any one of Aspects 1-2, wherein the particles range from 20 wt % of the aqueous dispersion to 80 wt % of the dispersion.

Aspect 4 provides the aqueous dispersion according to any one of Aspects 1-3, wherein the polycarbonate component ranges from 50 wt % to 100 wt % of each of the particles.

Aspect 5 provides the aqueous dispersion according to any one of Aspects 1-4, wherein the polycarbonate component ranges from 90 wt % to 100 wt % of each of the particles.

Aspect 6 provides the aqueous dispersion according to any one of Aspects 1-5, wherein the polycarbonate component comprises one or more polycarbonates, wherein the polycarbonates are the same or different polycarbonates.

Aspect 7 provides the aqueous dispersion of any of the preceding Aspects, wherein the polycarbonate component comprises at least one a linear homopolycarbonate, a branched, cyanophenol end-capped homopolycarbonate, a copolycarbonate comprising bisphenol A carbonate units and bisphenol carbonate units comprising 12 to 60 carbon atoms, a poly(aromatic ester-carbonate), poly(carbonate-siloxane), a poly(ester-siloxane-carbonate), and a poly(aliphatic ester-carbonate).

Aspect 8 provides the aqueous dispersion of Aspect 7, wherein the polycarbonate includes a repeating unit chosen from resorcinol, 2,2-bis(4-hydroxyphenyl) propane, 3,3-bis(4-hydroxyphenyl) phthalimidine, 2-phenyl-3,3′-bis(4-hydroxyphenyl) phthalimidine, 3,3-bis(4-hydroxyphenyl)-2-phenylisoindolin-1-one), 1,1-bis (4-hydroxy-3-methylphenyl)cyclohexane, 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane (isophorone bisphenol), or mixtures thereof.

Aspect 9 provides the aqueous dispersion of any of the preceding aspects, wherein the polycarbonate component comprises a polycarbonate copolymer.

Aspect 10 provides the aqueous dispersion of Aspect 9, wherein the polycarbonate is chosen from a copolymer comprising repeating units derived from bisphenol A carbonate units and 2-phenyl-3,3′-bis(4-hydroxyphenyl) phthalimidine carbonate units, a copolymer comprising repeating units of bisphenol A carbonate units and 1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane carbonate units a copolymer comprising bisphenol A carbonate units and 1,1-bis(4-hydroxy-3-methylphenyl)-3,3,5-trimethylcyclohexane isophorone bisphenol carbonate units copolymer comprising repeating units chosen from bisphenol A carbonate units and siloxane units.

Aspect 11 provides the aqueous dispersion of Aspect 10, wherein the repeating units of the polycarbonate copolymer are each independently in random, block, or alternating configuration.

Aspect 12 provides the aqueous dispersion according to any one of the preceding aspects, wherein the individual particles of the plurality of particles have a D₉₀ in a range of 300 nm to 4000 nm, preferably a D₉₀ in a range of 300 nm to 1000 nm, or a range of 300 nm to 600 nm, preferably the particles have a D₉₈ of 340 nm to 345 nm, e.g., a D₉₈ of 342 nm.

Aspect 13 provides the aqueous dispersion according to any one of the preceding aspects, wherein the particles have a D90 in a range of 500 nm to 600 nm.

Aspect 14 provides the aqueous dispersion according to any one of the preceding aspects, wherein the aqueous dispersion is substantially free of phase separation between the plurality of particles and the surfactant component for a time period of greater than 1 month, preferably greater than 12 months.

Aspect 15 provides the aqueous dispersion according to any one of the preceding aspects, wherein the particles have a monomodal particle size distribution.

Aspect 16 provides the aqueous dispersion of any one of the preceding aspects, wherein the particles have a substantially spherical shape.

Aspect 17 provides the aqueous dispersion of any one of the preceding aspects, wherein the particles are substantially free of edges.

Aspect 18 provides the aqueous dispersion according to any one of Aspects 1-14, wherein the particles have a bimodal particle size distribution.

Aspect 19 provides the aqueous dispersion according to any one of the preceding aspects, wherein the particles have a sub-micron diameter.

Aspect 20 provides the aqueous dispersion according to any one of the preceding aspects, wherein the plasticizer component ranges from 1 wt % to 20 wt % of the aqueous dispersion, preferably wherein the aqueous dispersion comprises from 1 wt % to 30 wt % surfactant component, and wherein the total weight percentage in the aqueous dispersion is 100 wt %..

Aspect 21 provides the aqueous dispersion according to any one of the preceding aspects, wherein the plasticizer component ranges from 13 wt % to 16 wt % of the aqueous dispersion.

Aspect 22 provides the aqueous dispersion according to any one of the preceding aspects, wherein the plasticizer component comprises two or more plasticizers.

Aspect 23 provides the aqueous dispersion of Aspect 22, wherein one of the plasticizers ranges from 50 wt % to 100 wt % of the plasticizer component.

Aspect 24 provides the aqueous dispersion of Aspect 22, wherein one of the plasticizers ranges from 90 wt % to 100 wt % of the plasticizer component.

Aspect 25 provides the aqueous dispersion of any one of the preceding aspects, wherein the plasticizer comprises a material chosen from an aliphatic monoalkyl ester, an aromatic monoalkyl ester, an aliphatic polyalkyl ester, an aromatic polyalkyl ester, a polyalkyl ester of an aliphatic alcohol, a phosphonic polyalkyl ester, an aliphatic poly(alkoxylated) ester, an aromatic poly(alkoxylated) ester, a poly(alkoxylated) ether of an aliphatic alcohol, a poly(alkoxylated) ether of a phenol, or mixtures thereof.

Aspect 26 provides the aqueous dispersion of any one of the preceding aspects, wherein the plasticizer comprises a material chosen from an organophosphorous compound, a halogenated compound, a metal hydroxide, or mixtures thereof.

Aspect 27 provides the aqueous dispersion of any one of the preceding aspects, wherein the plasticizer comprises an organophosphorous compound which is chosen from triethyl phosphate, tris(2-chloropropyl)phosphate, triphenyl phosphate, diphenyl cresyl phosphate, resorcinol diphenylphosphate, resorcinol diphosphate, trialkyl phosphites, triaryl phosphites, mixed alkyl-aryl phosphites, diethyl ethyl phosphonate, dimethyl methyl phosphonate, melamine polyphosphate, ammonium polyphosphates, aluminum tris(diethyl phosphinate), or mixtures thereof.

Aspect 28 provides the aqueous dispersion of any one of the preceding aspects, wherein the plasticizer comprises resorcinol diphenyl phosphate, preferably the plasticizer consists of resorcinol diphenyl phosphate.

Aspect 29 provides the aqueous dispersion of any one of the preceding aspects, wherein the plasticizer comprises a halogenated compound which is chosen from a chlorendic acid derivative, a chlorinated paraffin; an organobromine, a decabromodiphenyl ether, a decabromodiphenyl ethane, a polymeric brominated compound, a brominated polystyrene, a brominated carbonate oligomer, a brominated epoxy oligomer, a tetrabromophthalic anyhydride, or mixtures thereof.

Aspect 30 provides the aqueous dispersion of any one of the preceding aspects, wherein the plasticizer comprises a metal hydroxide which is chosen from magnesium hydroxide, aluminum hydroxide, cobalt hydroxide, hydrates thereof, or mixtures thereof.

Aspect 31 provides the aqueous dispersion according to any one of the preceding aspects, wherein a minimum film formation temperature of the aqueous dispersion ranges from 100° C. to 180° C.

Aspect 32 provides the aqueous dispersion according to any one of the preceding aspects, wherein a minimum film formation temperature of the aqueous dispersion ranges from 165° C. to 180° C.

Aspect 33 provides the aqueous dispersion according to any one of the preceding aspects, wherein a minimum film formation temperature of the aqueous dispersion ranges from 10° C. to 50° C. less than a corresponding aqueous dispersion that is free of the plasticizer component.

Aspect 34 provides the aqueous dispersion of any one of the preceding aspects, wherein the plasticizer is resorcinol diphenyl phosphate.

Aspect 35 provides the aqueous dispersion according to any one of the preceding aspects, wherein the surfactant component ranges from 1 wt % to 20 wt % of the aqueous dispersion.

Aspect 36 provides the aqueous dispersion according to any one of the preceding aspects, wherein the surfactant component ranges from 5 wt % to 15 wt % of the aqueous dispersion.

Aspect 37 provides the aqueous dispersion according to any one of the preceding aspects, wherein the surfactant component comprises two or more surfactants.

Aspect 38 provides the aqueous dispersion of Aspect 37, wherein, when two or more surfactants are present, one of the surfactants comprises 50 wt % to 100 wt % of the surfactant component.

Aspect 39 provides the aqueous dispersion of Aspect 38, wherein one of the surfactants comprises 90 wt % to 100 wt % of the surfactant component.

Aspect 40 provides the aqueous dispersion of any one of the preceding aspects, wherein the surfactant comprises at least one of an anionic surfactant, a cationic surfactant, or a non-ionic surfactant.

Aspect 41 provides the aqueous dispersion of Aspect 40, wherein the surfactant comprises an anionic surfactant which is at least one of stearate sodium, dodecyl sulfate sodium, dodecyl benzene sulfonate sodium, alginic acid sodium, glycolic acid ethoxylate 4-tert butylphenyl ether, glycolic acid ethoxylate lauryl ether, glycolic acid ethoxylate 4-nonylphenyl ether, poly(ethylene glycol) 4-nonylphenyl 3-sulfopropyl ether potassium salt, sodium dioctyl sulphosuccinate, or a mixture thereof.

Aspect 42 provides the aqueous dispersion of any one of the preceding aspects, wherein the surfactant comprises a non-ionic surfactant which is at least one of poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol), poly(ethylene glycol) sorbitan tetraoleate, polyethylene-block-poly(ethylene glycol), sorbitan monopalmitate, polyoxyethylenesorbtan monooleate, or a mixture thereof.

Aspect 43 provides the aqueous dispersion according to any one of the preceding aspects, further comprising a solvent component.

Aspect 44 provides the aqueous dispersion of Aspect 43, wherein a solvent of the solvent component is selected from dichloromethane, chloroform, demethylformamide, dimethyl sulfate, tetrahydrofuran, or mixtures thereof.

Aspect 45 provides the aqueous dispersion of any one of the preceding aspects, further comprising an additive comprising a particulate filler, antioxidant, heat stabilizer, light stabilizer, ultraviolet light stabilizer, UV absorbing additive, NIR absorbing additive, IR absorbing additive, plasticizer, lubricant, release agent, antistatic agent, anti-fog agent, antimicrobial agent, colorant, laser marking additive, surface effect additive, radiation stabilizer, flame retardant, anti-drip agent, a fragrance, a fiber, or a mixture thereof.

Aspect 46 provides the aqueous dispersion of any one of the preceding aspects, further comprising a flow promoter comprising an unmodified fumed metal oxide, a hydrophobic fumed metal oxide, a hydrophilic fumed metal oxide, hydrated silica, amorphous alumina, glassy silica, glassy phosphate, glassy borate, glassy oxide, titania, talc, mica, kaolin, attapulgite, calcium silicate, magnesium silicate, or a mixture thereof.

Aspect 47 provides an article produced from the aqueous dispersion of any one of the preceding aspects, comprising: a plurality of particles, each particle comprising a polycarbonate component, wherein individual particles have a D90 in a range of 300 nm to 4000 nm; a plasticizer component; and a surfactant component.

Aspect 48 provides the article of Aspect 47, wherein the article is a sizing, is a film, a powder, a coating, a tie layer, an adhesive, a composite unidirectional tape, a three-dimensional printed article, or a woven.

Aspect 49 provides the article according to any one of Aspects 47-48, wherein the article is a tie layer to bond metal to a fluoropolymer, a powder coating, an epoxy-toughening coating, or a coating on a fiber.

Aspect 50 provides a method of forming the aqueous dispersion of any of Aspects 1-46, the method comprising: combining an organic phase and an aqueous phase to form an first solution, the organic phase comprising a polycarbonate component and a solvent component, the aqueous phase comprising water and a surfactant component; heating the first solution to evaporate the solvent and form a second solution; mixing at least one of the first solution and the second solution; and combining a plasticizer component with the second solution to form the aqueous dispersion.

Aspect 51 provides the method of Aspect 50, wherein combining the organic phase and the aqueous phase is performed in a drop-wise manner.

Aspect 52 provides the method of any of Aspects 50-51, wherein the mixing is under shear at 7,000 to 30,000 rpm

Aspect 53 provides the method of any of Aspects 50-52, wherein the mixing is under shear at 15,000 to 25,000 rpm

Aspect 54 provides the method of any of Aspects 50-53, wherein the mixing is under high shear for 2 to 40 minutes.

Aspect 55 provides the method of any of Aspects 50-54, wherein the mixing is under high shear for 8 to 30 minutes.

Aspect 56 provides the method of any of Aspects 50-55, further comprising removing the solvent component.

Aspect 57 provides the method of any of Aspects 50-56, wherein removing the solvent component comprises heating the second solution to a temperature at or above the boiling point of the solvent component but below the boiling point of the water.

Aspect 58 provides the method of any of Aspects 50-57, further comprising adding the second solution to a second aqueous composition.

Aspect 59 provides the method according to any one of Aspects 50-58, wherein the surfactant component is an anionic surfactant and the particles have a D90 in a range of 300 nm to 400 nm.

Aspect 60 provides the method according to any one of Aspects 50-59, wherein the surfactant component is an anionic surfactant and the particles have a D98 of 342 nm.

Aspect 61 provides a product formed according to the method of any one of Aspects 50-60.

Aspect 62 provides a sized carbon fiber tow, comprising: a polycarbonate sizing on a carbon fiber tow, wherein the polycarbonate sizing has a concentration of volatile organic compounds less than 10 ppm; and an average sizing content of at least 0.5 wt % of the carbon fiber tow with a coefficient of variation less than 15%.

Aspect 63 provides the sized carbon fiber tow of Aspect 62, wherein the coefficient of variation in sizing content is less than 11%.

Aspect 64 provides the sized carbon fiber tow of any one of Aspects 62-63, wherein the concentration of volatile organic compounds is less than 5 ppm.

Aspect 65 provides the sized carbon fiber tow of any one of Aspects 62-64, wherein the concentration of volatile organic compounds is less than 2 ppm.

Aspect 66 provides the sized carbon fiber tow of any one of Aspects 62-65, wherein the average sizing content ranges from 0.9 wt % to 2.4 wt % of the carbon fiber tow.

Aspect 67 provides the sized carbon fiber tow of any one of Aspects 62-66, wherein the volatile organic compounds are members selected from the group consisting of methylene chloride, perchloro-ethylene, methyl-tertiary butyl ether (MTBE), N-Methyl-2-pyrrolidone, t-butyl acetate, dimethylformamide (DMF), dioxane, dichloromethane (DCM), n-alkane (C12-C18), dimethyl carbonate, cyclopentanone, chloroform, formaldehydes, acetone, toluene, xylene, benzene, hexane, diphenyl carbonate, and combinations thereof.

Aspect 68 provides a method of preparing the sized carbon fiber tow of any one of Aspects 62-67, comprising: spreading the carbon fiber tow over a spreader unit at a throughput line speed of at least 0.3 meters/minute and forming spreaded carbon fibers; sizing the spreaded carbon fibers in a sizing bath containing an aqueous polycarbonate sizing dispersion and forming sized carbon fibers; and drying the sized carbon fibers and obtaining the sized carbon fiber tow.

Aspect 69 provides the method according to Aspect 68, wherein the carbon fiber tow is optionally unspooled over a bobbin prior to spreading.

Aspect 70 provides the method according to any one of Aspects 68-69, wherein the sized carbon fiber tow is optionally winded into a spool for further processing.

Aspect 71 provides the method of any one of Aspects 68-70, wherein the sized carbon fibers are dried in an oven operating at a temperature ranging from 150° C. to 300° C.

Aspect 72 provides the method of any one of Aspects 68-71, wherein the aqueous polycarbonate sizing dispersion comprises: a polycarbonate component comprising, a plurality of polycarbonate resin particles, wherein the plurality of polycarbonate resin particles has a dispersion characterized by having a D90 value ranging from 300 nm to 4000 nm; a plasticizer component; and a surfactant component.

Aspect 73 provides the method of any one of Aspects 68-71, wherein the aqueous polycarbonate sizing dispersion is the aqueous dispersion of any one of Aspects 1-46.

Aspect 74 provides the method according to any one of Aspects 72-73, wherein the plurality of polycarbonate resin particles is present at a concentration ranging from 0.5 wt % to 5 wt % of the aqueous polycarbonate sizing dispersion.

Aspect 75 provides the method according to any one of Aspect 72-74, wherein the aqueous polycarbonate sizing dispersion has a minimum film formation temperature (MFFT) ranging from 100° C. to 180° C.

Aspect 76 provides the method according to any one of Aspects 72-75, wherein the plurality of polycarbonate resin particles has a monomodal size distribution.

Aspect 77 provides the method according to any one of Aspects 72-76, wherein the plasticizer component comprises a member selected from the group consisting of esters, organophosphorous compounds, ethers, hydrocarbons, paraffins, sulphonamides, sulfonates, terephthalates, terpenes, trimellitates, and combinations thereof.

Aspect 78 provides the method according to any one of Aspects 72-77, wherein the plasticizer component comprises an organo-phosphorous compound selected from a group consisting of resorcinol bis-(diphenylphosphate) (RDP), trialkyl phosphates, triaryl phosphates, phosphites, phosphonates, polyphosphates, polyphosphites, polyphosphonates, phosphinates, and combinations thereof.

Aspect 79 provides the method according to any one of Aspects 72-78, wherein the plasticizer component is resorcinol bis-(diphenylphosphate) (RDP).

Aspect 80 provides the method according to any one of Aspects 72-79, wherein the plasticizer component is present at a concentration ranging from 1 wt % to 20 wt % of the aqueous polycarbonate sizing dispersion.

Aspect 81 provides the method according to any one of Aspects 72-80, wherein the surfactant component is selected from a group consisting of anionic surfactants, cationic surfactants, non-ionic surfactants, and blends thereof.

Aspect 82 provides the method according to any one of Aspects 72-81, wherein the surfactant component is present at a concentration ranging from 1 wt % to 20 wt % of the aqueous polycarbonate sizing dispersion. 

1. An aqueous dispersion comprising: a plurality of particles each particle comprising a polycarbonate component, wherein individual particles have a value of the particle diameter at 90% of the cumulative distribution of particles as determined by analyses of a dynamic light scattering plot (D₉₀) in a range of 300 nm to 4,000 nm and wherein the polycarbonate component comprises at least one of a linear homopolycarbonate of a bisphenol, a branched, cyanophenol end-capped homopolycarbonate, a copolycarbonate comprising bisphenol A carbonate units and bisphenol carbonate units comprising 12 to 60 carbon atoms, a poly(aromatic ester-carbonate), poly(carbonate-siloxane), a poly(ester-siloxane-carbonate), and a poly(aliphatic ester-carbonate); a plasticizer component; and a surfactant component, wherein polycarbonate means a polymer or copolymer having repeating structural carbonate units of Formula (I):

wherein at least 60 percent of the total number of R¹ groups are aromatic, or each R¹ contains at least one C6-30 aromatic group.
 2. The aqueous dispersion of claim 1, wherein the particles are present in an amount of 50 wt % to 90 wt % of the aqueous dispersion, preferably wherein the aqueous dispersion comprises from 1 wt % to 20 wt % plasticizer component, preferably wherein the aqueous dispersion comprises from 1 wt % to 30 wt % surfactant component, and wherein the total weight percentage in the aqueous dispersion is 100 wt %.
 3. The aqueous dispersion of claim 1, wherein the individual particles have a D₉₀ in a range of 300 nm to 4000 nm, preferably in a range of 300 nm to 600 nm, or in a range of 300 nm to 400 nm, preferably the particles have a D₉₈ of 340 nm to 345 nm.
 4. The aqueous dispersion of claim 1, wherein the aqueous dispersion is substantially free of phase separation between the plurality of particles and the surfactant component for a time period of greater than 1 month, preferably greater than 12 months.
 5. The aqueous dispersion of claim 1, wherein a plasticizer of the plasticizer component is resorcinol diphenyl phosphate.
 6. The aqueous dispersion of claim 1, wherein the surfactant component is an anionic surfactant.
 7. The aqueous dispersion of claim 1, wherein the plurality of particles has a monomodal size distribution.
 8. An article produced from the aqueous dispersion of claim
 1. 9. The article of claim 8, wherein the article is a powder, a film, a sizing, a coating, a tie layer, an adhesive, a composite unidirectional tape, a three-dimensional printed article, or an article of woven fiber.
 10. A method of forming the aqueous dispersion of claim 1, the method comprising: combining an organic phase and an aqueous phase to form a first solution, the organic phase comprising a polycarbonate component and a solvent component, the aqueous phase comprising water and a surfactant component; heating the first solution to evaporate the solvent component; and form a second solution; and combining a plasticizer component with the second solution to form the aqueous dispersion.
 11. The method of claim 10, further comprising mixing at least one of the first solution or the second solution, wherein the mixing is performed under shear at 7,000 to 30,000 rpm
 12. The method of claim 10, wherein heating the first solution comprises heating the first solution to a temperature at or above the boiling point of the solvent component and below the boiling point of the water.
 13. A sized carbon fiber tow, comprising: a polycarbonate sizing on a carbon fiber tow, wherein polycarbonate means a polymer or copolymer having repeating structural carbonate units of Formula (I):

wherein at least 60 percent of the total number of R¹ groups are aromatic, or each R¹ contains at least one C6-30 aromatic group, and wherein the polycarbonate sizing has a concentration of volatile organic compounds less than 10 ppm, preferably less than 5 ppm, or less than 2 ppm; and an average sizing content of at least 0.5 wt % of the carbon fiber tow with a coefficient of variation less than 15%, preferably less than 11% wherein the average sizing content is an average of sizing content measured according to ASTM D2584 various points across a predetermined length of the carbon fiber tow, and sizing content is ((w₁−w₀)/w₀)×100, wherein, w₁=weight of sized carbon fiber tow; w₀=weight of carbon fiber tow (unsized) and wherein coefficient of variation is 100 times standard deviation, S, divided by the average sizing content, where S=[Σ(x_(i)−x_(a))²/(n−1)]^(1/2).
 14. The sized carbon fiber tow of claim 13, wherein the average sizing content ranges from 0.9 wt % to 2.4 wt % of the carbon fiber tow.
 15. The sized carbon fiber tow of claim 13, wherein the volatile organic compounds are members selected from the group consisting of methylene chloride, perchloro-ethylene, methyl-tertiary butyl ether (MTBE), N-Methyl-2-pyrrolidone, t-butyl acetate, dimethylformamide (DMF), dioxane, dichloromethane (DCM), n-alkane (C12-C18), dimethyl carbonate, cyclopentanone, chloroform, formaldehydes, acetone, toluene, xylene, benzene, hexane, diphenyl carbonate, or combinations thereof.
 16. The sized carbon fiber tow of claim 13, wherein the polycarbonate sizing is formed from the aqueous dispersion of claim
 1. 17. A method of preparing the sized carbon fiber tow of claim 13, comprising: spreading the carbon fiber tow over a spreader unit at a throughput line speed of at least 0.3 meters/minute and forming spread carbon fibers; sizing the spread carbon fibers in a sizing bath containing an aqueous polycarbonate sizing dispersion and forming sized carbon fibers; and drying the sized carbon fibers to obtain the sized carbon fiber tow.
 18. The method of claim 17, wherein the sized carbon fibers are dried in an oven operating at a temperature ranging from 150° C. to 300° C.
 19. The method according to claim 17, wherein the aqueous polycarbonate sizing dispersion has a minimum film formation temperature (MFFT) according to ASTM D2354 ranging from 100° C. to 180° C. 